Industrial fields are paying more attention to musculoskeletal disorder than ever to prevent accidents and work-induced diseases. Since workers working on the spot are exposed to various harmful factors according to each work environment, they are susceptible to the musculoskeletal disorder. Occupational factors that cause the musculoskeletal disorder are very diverse and, in most cases, the disease is developed by more than one harmful factors acting together. The musculoskeletal disorder is a chronic health problem in the musculoskeletal system which is caused by fatigue accumulated in muscle and bones. The accumulated fatigue injures the human body and develops pain and sensory dysfunction. The factors that cause the musculoskeletal disorder are uncomfortable work posture, excessive use of power, continued static state, lack of rest, excessive work repetition, limited work place, inappropriate work environment such as temperature, humidity, noise and lighting.
The development of musculoskeletal causes many social problems such as wage compensation cost, increasing medical expenses, deteriorating productivity and quality of living. Accordingly, the Ministry of Labor of the Republic of Korea has brought in force “Regulations on Industrial health standards” Amendment, whose selling point is that a business owner should investigate harmful factors on work which may induce musculoskeletal disorder one every three years, since Jul. 12, 2003, to prevent the musculoskeletal disorder.
As an increasing number of people are concerned with the musculoskeletal disorder, diverse forms of apparatuses are developed to measure force applied to a human body when a worker works. To take an example, Korean Patent Publication No. 10-2001-003939 discloses an apparatus for measuring a force that a human hand applies to a joystick by attaching a sensor to the joystick. U.S. Pat. No. 5,317,916 discloses an apparatus for measuring a force applied to two stick handles when a human being grabs the handles by setting up a sensor between the two stick handles.
The apparatuses of the cited references have limitation that they simply measure a grasping power, because workers cannot get the test while wearing the apparatuses in the hands and working. Therefore, there is a problem that it is hard to measure a physical force applied by a human body when a worker is exposed to diverse work environment.